Cogon Grass for Oil Sorption: Characterization and Sorption Studies

Abstract

Cogon grass (Imperata cylindrica), an invasive, unwanted grass was used and evaluated for its applicability for the sorption of engine oil. Other than dried and ground for smaller size, no notable treatment was performed on the cogon grass. The physical and chemical properties of cogon grass were characterized by ash content, bulk density, pH slurry, and Field Emission Scanning Electron Microscopy (FESEM). The oil sorption was performed in a batch adsorption system. The effects of contact time, dosage of adsorbent and oil retention were investigated. The bulk density and ash content of the prepared carbon was 0.34 g/ml and 7.80 %, respectively. The pH slurry value was near neutrality (6.48). FESEM micrograph of cogon grass showed jagged and rough surface. FTIR spectra revealed the presence of aromatic rings of lignin and some aromatic compounds associated with CH. Carbon, hydrogen and nitrogen (CHN) analysis revealed that 41% of cogon grass consists of carbon. The cogon grass was observed to wet oil almost instantly with sorption equilibrium time of 5 min. The dose of cogon grass was found to slightly affect the sorption capacity. Oil retention experiments reveal the good ability of cogon grass to hold oil with about 96% retention after 24 h dripping. This study may provide an insight on the usefulness of cogon grass for removal of engine oils.